/*
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
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/*
 * Copyright (c) 2009 by Oracle Corporation. All Rights Reserved.
 */

package javax.xml.stream.events;

import java.io.Writer;
import javax.xml.namespace.QName;

/**
 * This is the base event interface for handling markup events.
 * Events are value objects that are used to communicate the
 * XML 1.0 InfoSet to the Application.  Events may be cached
 * and referenced after the parse has completed.
 *
 * @version 1.0
 * @author Copyright (c) 2009 by Oracle Corporation. All Rights Reserved.
 * @see javax.xml.stream.XMLEventReader
 * @see Characters
 * @see ProcessingInstruction
 * @see StartElement
 * @see EndElement
 * @see StartDocument
 * @see EndDocument
 * @see EntityReference
 * @see EntityDeclaration
 * @see NotationDeclaration
 * @since 1.6
 */
public interface XMLEvent extends javax.xml.stream.XMLStreamConstants {

    /**
     * Returns an integer code for this event.
     * @see #START_ELEMENT
     * @see #END_ELEMENT
     * @see #CHARACTERS
     * @see #ATTRIBUTE
     * @see #NAMESPACE
     * @see #PROCESSING_INSTRUCTION
     * @see #COMMENT
     * @see #START_DOCUMENT
     * @see #END_DOCUMENT
     * @see #DTD
     */
    public int getEventType();

    /**
     * Return the location of this event.  The Location
     * returned from this method is non-volatile and
     * will retain its information.
     * @see javax.xml.stream.Location
     */
    javax.xml.stream.Location getLocation();

    /**
     * A utility function to check if this event is a StartElement.
     * @see StartElement
     */
    public boolean isStartElement();

    /**
     * A utility function to check if this event is an Attribute.
     * @see Attribute
     */
    public boolean isAttribute();

    /**
     * A utility function to check if this event is a Namespace.
     * @see Namespace
     */
    public boolean isNamespace();

    /**
     * A utility function to check if this event is a EndElement.
     * @see EndElement
     */
    public boolean isEndElement();

    /**
     * A utility function to check if this event is an EntityReference.
     * @see EntityReference
     */
    public boolean isEntityReference();

    /**
     * A utility function to check if this event is a ProcessingInstruction.
     * @see ProcessingInstruction
     */
    public boolean isProcessingInstruction();

    /**
     * A utility function to check if this event is Characters.
     * @see Characters
     */
    public boolean isCharacters();

    /**
     * A utility function to check if this event is a StartDocument.
     * @see StartDocument
     */
    public boolean isStartDocument();

    /**
     * A utility function to check if this event is an EndDocument.
     * @see EndDocument
     */
    public boolean isEndDocument();

    /**
     * Returns this event as a start element event, may result in
     * a class cast exception if this event is not a start element.
     */
    public StartElement asStartElement();

    /**
     * Returns this event as an end  element event, may result in
     * a class cast exception if this event is not a end element.
     */
    public EndElement asEndElement();

    /**
     * Returns this event as Characters, may result in
     * a class cast exception if this event is not Characters.
     */
    public Characters asCharacters();

    /**
     * This method is provided for implementations to provide
     * optional type information about the associated event.
     * It is optional and will return null if no information
     * is available.
     */
    public QName getSchemaType();

    /**
     * This method will write the XMLEvent as per the XML 1.0 specification as Unicode characters.
     * No indentation or whitespace should be outputted.
     *
     * Any user defined event type SHALL have this method
     * called when being written to on an output stream.
     * Built in Event types MUST implement this method,
     * but implementations MAY choose not call these methods
     * for optimizations reasons when writing out built in
     * Events to an output stream.
     * The output generated MUST be equivalent in terms of the
     * infoset expressed.
     *
     * @param writer The writer that will output the data
     * @throws XMLStreamException if there is a fatal error writing the event
     */
    public void writeAsEncodedUnicode(Writer writer) throws javax.xml.stream.XMLStreamException;

}
